Band brake



May 13, 1952 R. F. GAMUNDI BAND BRAKE Filed D90. 17, 1949 Patented May13, 1952 BAND BRAKE Reynold F. Gamundi, Mayfield Heghts, Ohio, assignorto Eaton Manufacturing Company, Cleveland, Ohio, a corporation of OhioApplication December 17, 1949, Serial No. 133,639

4 Claims. 1

This invention relates to band brakes and more particularly to two-wayband brakes primarily, though not exclusively, useful for braking andlocking rotary drums in automatic transmissions or the like.

The object of the invention is the provision of an improved two-way bandbrake which is adapted for braking in either direction of rotation,wherein substantially the entire effective length of `the brake band isavailable for braking in either direction of rotation. In general, thisis accomplished by providing a magnetic brake drum and a band coiledaround the drum with electromagnetic shoes attached to the band at theends of the band. The shoes are adapted magnetically to cling to thedrum upon being energized. An anchor pin is fixed with respect to thedrum extending longitudinally and outward of the periphery of the drum.The shoes have ears extending radially outward on opposite sides of thepin, the ears being spaced apart a distance greater than the width ofthe pin. With this arrangement, the entire length of the band betweenshoes is effective for braking in one direction or another of rotationsimply by causing the shoes to cling to the drum, as will be made clear.Other features will be in part apparent and in part pointed outhereinafter.

The invention accordingly comprises the elements and combinations ofelements, features of construction, and arrangements of parts which willbe exemplified in the structures hereinafter described, and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawing, in which one of various possibleembodiments of the invention is illustrated,

Fig. 1 is a diagrammatic View illustrating the basic principles of theinvention;

Fig. 2 is a side -elvation of a brake embodying the invention, withparts broken away and shown in section; and,

Fig. 3 is a transverse section taken on line 3-3 of Fig. 2, with partsbroken away and shown in section.

Similar reference characters indicate corresponding parts throughout theseveral views of the drawing.

Fig. 1 diagrammatically illustrates the basic principle of the operationof the invention. A rotary drum member is shown at A and a bandanchoring Vmember at B. These are relatively rotary. Usually, the drummember is rotary and the band anchoring member stationary. A frictionstrap or band C is loosely coiled around the drum and has both its endsanchored (with play) to the anchoring member at D. At E are shown twoshoes attached to the band at spaced points along its length. Means isprovided whereby the shoes may be caused to cling to the drum. Forexample, the drum may be made of magnetic material and each shoe anelectromagnet adapted magnetically to cling to the drum upon beingenergized or excited. With this arrangement, assuming the drum to berotary and the band anchoring member stationary, the entire portion ofthe length of the band between the two shoes is effective for brakingupon rotation of the driun in either direction.

Referring now to Figs. 2 and 3 of the drawing, which illustrate apractical embodiment of the invention, there is shown at I a casingconstituting a brake housing. Rotary in the housing is a brake drum 3,which is made of magnetic material such as iron or soft steel, and whichhas a cylindric periphery. The drum is shown as fixed on a shaft 5`iournalled in bearings (not illustrated) in the end walls of thehousing I A lined flexible brake band 1 is helically coiled around thedrum. An electromagnetic shoe 9 is attached at l to one end of the band.A second electromagnetic shoe |3 is attached at IE to the other end ofthe band. The band is coiled in counterclockwise direction from shoe |3to shoe 9 as Viewed in Fig. 3.

Each of the shoes 9 and 13 is also composed of magnetic material such asiron or soft steel, formed to fit against the periphery of the drum andto contain a magnetizing coil I'l. As shown, each shoe has an outer wall|9 with its outside face 2| curved on an arc centered in the axis of thedrum, and side walls 23 and a central wall 25 extending from the outerwall toward the drum with their inner edges curved as indicated at 21 tofit against the periphery of the drum. The central wall 25 forms a polearound which is fitted the coil I'l. The side walls project somewhatoutward of the outer wall |9 and their outer edges are curved, asindicated at 29, on an arc centered in the axis of the drum.

At 3| is shown an anchoring member which consists of a pin extendinglongitudinally of the housing and located outward of the periphery ofthe drum. The pin is fixed in a pair of longitudinally spaced bosses 33formed on the interior of the peripheral wall of the housing. The shoes9 and 13 are located between the pin and the L drum and are spaced apartlongitudinally with 4` respect to the housing. The pin extends betweenradially outwardly extending ears 35 and 31 on shoe 9 and betweenradially outwardly extending ears 39 and 4| on shoe |3. Ears and 31 onshoe 9 are spaced apart on the arc of the outer face of the shoe adistance greater than the diameter of pin 3| so that the shoe 9 isadapted for movement in an arc around the axis of the drum as limited bythe engagement of the ears with the pin. Similarly, ears 39 and 4| onthe shoe |3 are spaced apart on the arc of the outer face of the shoe adistance greater than the i diameter'of pin 3| so that the shoe |3 isalso adapted for movement in an arc around the axis of the drum, aslimited by the engagement of the ears with the pin. The ears on theshoes are formed as integral extensions of the side walls of the shoes.The ears 35 on the shoe-9 and the ears 39 on the shoe |3 are the endears of the shoe and brake band assembly.

The brake band 1 is of such length that, with the band loosely coiledaround the drum, ears 35 on shoe Bengage the pin 3| and ears 39 on shoe|3 engage the pin, as .shown in Fig; 3. Thus, while shoe 9 is anchoredagainst clockwise movement as viewed in Fig. 3 and anehors therespective end of the lband against clockwise movement as viewed in Fig.3, it may move counterclock- Wise within the limit'imposed by ears 31,and while shoe |3 is anchored against counterclock- Wise movement by theears v39 and ianchors the respective end of the vband againstcounterclock- Wise movement, it may move clockwise within the limitimposed by ears 4|. i

The shoes are lightly biased against the periphery' of the drum byspring-loaded rollers 43 which bear against the outside arcuate faces 2|of the outer walls |9 of the shoes. Rollers 43 are mounted on shafts 45supported in bearing members 41 on studs 49. Studs 49 slide in radialsockets 5|V formed on the interior of the' wall of the housing and arebiased radially inward by compression springs 53 in the sockets, thelatter reacting from the bases of the sockets against the ends of thestuds. V i

The magnetizing coils |'l of the shoes 9 and |3 are adapted to beenergized or excited through suitable leads (not shown). Normally,both'coils are deenergized and the drum rotates freely within the brakeband 1, the band being loose and shoes 9 and |3 voffering no substantialimpedance to rotation. Assuming that the drum is rotatingcounterclockwise as viewed in Fig. 3, and it is desired to-stop it, bothcoils |`l are en- .ergized The shoe 9 .thereupon 'magnetically clings tothe drum and is :carriedaaround with the drum Vcounterclockwise :as'indicated Vby the arrow F in Fig. 3, thereby initiating tightening of-the brake band.

This action is permitted byithe play in the connection ofV the shoe 9`tothe anchor pin 3|, and is followed by a frictional servo actionoccasioned' by the'friction between the brake Vband and the drum whichcauses the brake 'band tightly to grip and lock the drum againstrotation. The final looking action of theband isnot dependent uponthemagnetic clinging of the shoe 9 to the drum, this magnetic clingingonly initiating the tightening of the band. While,'as above described,the coil |1 for shoe |3V is'here energized, thisv is of only minoreffect in braking.

' If 'desired, to stop counterclockwise rotation of the drum, only thecoil for shoe 9 need be energized. When the shoes .are deenergized, .the

brake'bandis released.

Assuming` that the drum is, rotating clockwise both coils are energized.The shoe |3 thereupon magnetically clings to the drum and is carriedaround with the drum clockwise, as indicated by the arrow G in Fig. 3,thereby initiating tightening of the brake band. This action ispermitted by the play in the connection of the shoe |3 to the pin 3|,and is followed by a frictional servo action occasioned by the fric'tionbetween the brake band and the drum which causes the brake band tightlyto grip and lock the drum against rotation. The final looking action ofthe band is not dependent upon the magnetic clinging of the shoe |3 tothe drum, this magnetic clinging only initiating the tightening of theband. As before, While coil for the shoe 9 is here energized, this is ofonly minor effect in braking. If desired, to stop clockwise rotation ofthe drum, only the coil for shoe |3 need be energized. When the shoesare deenergized, the brake band is released.

Thus, Vthe above-described arrangement is adapted to brake the drum ineither direction of rotation. An important feature of the constructionis that the same entire effective length of the z brake band iseffective for, braking in either direction.

`While in the above-described embodiment of the invention, the'brakedrum 3 is rotary and the brake band anchoring member is stationary, itwill be understood that this relationship may be reversed. That is, thebrake drum may be stationary and the brake band anchor rotary. Moreover.it is also contemplated that the invention may be applied in a systemWherein both the drum and the brake band anchor rotate, in which event,when the electromagnetic shoes` are energized, the drum and brake band.anchor will be clutched together and brought to the same speed. In thisevent, the device might becalled a clutch,

and the term "brake" is to be understood to refer to such a system,because the action is in fact a braking action wherein one element. isbrought .to `a relatively stationary relationship Vwith respect to theother when the brake is set.

'In view of the above, it Will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As many `changes .could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter vcontained in the above description or shown in theaccompanyingfdrawing shall' be interpreted 'as illustrative'and not in alimiting Sense.

I claim:

' 1. A- brakecomprising a housing, a magnetic brake drum rotary in thehousing, an anchor pin fixed in the housing extending longitudinally andlocated outward of the periphery of the drum, a lined brake band coiledaround the drum, and electromagnetic shoes attached to the band at itsends and 'located'between the pin and the drum,

' the shoes being adapted magnetically .to cling to the' drum upon beingenergized, each shoe having .ears extending radially outwardtherefrom'on opposite sides of the pin, the ears being spaced apart adistance greater than the width of the pin.

2. AV brake comprising a 'housing, Va magnetic brake drum rotary in thehousing, an anchor pin fixed in the housingiextending longitudinally andlocated outward of the periphery of the drum, a lined brake band coiledaround the drum, and

electromagnetic shoes attached to theband'at its I ends'jandV located.Vbetween the pin Vand the drum. ;the shoes being adapted magnetically to,cling to ffhedrum. uponb'eing energized, each shoe having an innercurved face adapted to fit against the periphery of the drum and anouter face curved on an arc centered in the axis of the drum and earsextending radially outward therefrom on opposite sdes of the pin, theears being spaced apart a distance greater than the width of the pm.

3. A brake comprising a housing, a magnetic brake drum rotary in thehousing, an anchor pin fixed in the housing extending longitudinally andlocated outward of the periphery of the drum, a lined brake band coiledaround the drum, and electromagnetic shoes attached to the band at itsends and located between the pin and the drum, the shoes being adaptedmagnetically to cling to the drum upon being energized, each shoe havingan inner curved face adapted to fit against the periphery of the drumand an outer face curved on an are centered in the axis of the drum andears extending radially outward therefrom on opposite sides of the pin,the ears being spaced apart a distance greater than the width of thepin, and spring-loaded rollers biasing the shoes toward the drum.

4. A brake comprising a, rotary magnetic brake REYNOLD F. GAMUNDI.

REFEREN CES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,447,837 Normanville Mar. 6,1923 FOREIGN PATENTS Number Country Date 25,283 Great Britain 1905`

